One potential hypothesis is that the region is a hot spot for gene insertion/deletion, with a specific selection pressure maintaining a particular function at that precise location in the genome.
Sense/antisense gene pairs with strong differences in expression may therefore be under specific selection pressure to prevent dsRNA formation.
Many studies attempt to identify the cause of population differentiation in phenotype through the study of a specific selection pressure.
Therefore it is reasonable to envisage that changes in the types and amounts of bitter compounds encountered in a specific environment may elicit specific selection pressures on Tas2rs.
Moreover, in all democracies parties are merely convenient chimeras, evolved under the specific selection pressures of their respective electoral ecosystems.
Moreover, determining which traits are the direct targets of selection as well as the specific selection pressures remains elusive (Hoffmann and Weeks 2007).
The requirement for the evolution of imprinted expression under this theory is simple: sex-specific selection pressure on a gene.
In all samples and in total contrast to the algae, the bacteria are seemingly subjected to a much higher location-specific selection pressure and appeared more affected by the availability of allochthonous carbon and the local geology.
This helps to explain the breed-specific selection pressure.
This is due to the fact that the X chromosome experiences sex-specific selection pressure [ 59].
Use of nonsynonymous substitutions with lineage-specific selection pressure change could lead to incorrect phylogenetic inference [ 72].
